The invention relates to a domestic appliance—in particular for the preparation of food—which can be switched to and fro between a standby mode and an operating mode (active mode). The domestic appliance has an electrical mains connection, at which an electrical mains voltage can be applied relative to a reference potential. It also comprises a main supply unit—for example a power pack—which supplies an electrical operating voltage from the mains voltage, specifically at an output. An electrical consumer (for example a main control unit and/or a sensor of the domestic appliance) is supplied with the operating voltage. The invention also relates to a method for operating such a domestic appliance.
In the prior art, a power pack is deployed in a domestic appliance. The power pack has the task of converting the electrical mains voltage, which is an alternating voltage, to an operating voltage, which is tailored to the electrical consumers of the domestic appliance, for example a control unit. The operating voltage is generally a direct voltage. Interest is primarily directed at a domestic appliance which has a standby mode. This standby mode is more energy-efficient than the operating mode and the domestic appliance consumes less energy than in operating mode. On the one hand, standby mode is intended to ensure that stored data is not lost and the operator can activate the domestic appliance quickly without having to reset the program code and restart the appliance. On the other hand, energy consumption is intended to be reduced to a minimum in standby mode.
In order to keep energy consumption as minimal as possible in standby mode, integrated circuits (IC) are used in the prior art, which can be switched to their own standby mode. For example voltage regulators with an integrated standby functionality are used here. When the voltage regulator is switched to standby mode, the connected consumers are also decoupled from the electrical voltage. A block circuit diagram of a known circuit arrangement 1 for a domestic appliance is shown in FIG. 1. It comprises a mains connection 2, at which a mains voltage UN is supplied, specifically relative to a reference potential 3. A main supply unit 4 is connected directly to the mains connection 2. It comprises a bridge rectifier 5—in some instances also with a smoothing capacitor (hold up)—as well as a power pack or voltage converter 6. Present at an output 7 of the main supply unit 4 is an operating voltage UB, which is produced from the mains voltage UN. The main supply unit 4 therefore supplies the operating voltage UB. This operating voltage UB is then used to supply a plurality of electrical consumers 8a to 8e, the number of which can in principle be arbitrary. The consumers 8a to 8e can comprise a main control unit of the domestic appliance, as well as sensors of any type and the like. The operating voltage UB is tapped at the output 7 by a voltage regulator 9 and stabilized or regulated. Also connected to the voltage regulator 9 is a further voltage regulator 10. While the consumers 8a and 8b are supplied by way of the voltage regulator 10, the voltage regulator 9 supplies the consumer 8c. The consumers 8d and 8e are in contrast coupled to the output 7 of the main supply unit 4 by way of a power divider 11. Both the voltage regulators 9, 10 and the power divider 11 are supplied as integrated circuits, which can be switched to an internal standby mode and therefore as it were deactivated. When the domestic appliance is switched to standby mode, corresponding control signals are emitted to the integrated circuits and said circuits are deactivated. This means that the consumers 8a to 8e are also isolated from the operating voltage UB.
In order to reduce the energy take-up of the domestic appliance as a whole to a minimum in standby mode, the consumption of the circuits in standby mode should also be correspondingly low. The energy consumption of the domestic appliance as a whole in standby mode is in fact a direct function of the energy take-up of the circuits. On the one hand therefore the number of circuits in the domestic appliance must be limited; on the other hand appropriate circuits must be selected and used, which have very low energy consumption in standby mode. This in turn is associated with a relatively major outlay when selecting the circuits, as well as with higher circuit costs. Also the main supply unit 4 consumes a relatively large amount of energy in standby mode. One particular challenge is to find a solution for reducing the outlay when selecting the circuits and the circuit costs to a minimum, without increasing the energy consumption of the domestic appliance as a whole in standby mode.